All You Can Eat: High Performance Capacity and Plasticity in the Common Big-Eared Bat, Micronycteris microtis (Chiroptera: Phyllostomidae)

Abstract

Ecological specialization and resource partitioning are expected to be particularly high in the species-rich communities of tropical vertebrates, yet many species have broader ecological niches than expected. In Neotropical ecosystems, Neotropical leaf-nosed bats (Phyllostomidae) are one of the most ecologically and functionally diverse vertebrate clades. Resource partitioning in phyllostomids might be achieved through differences in the ability to find and process food. We selected Micronycteris microtis, a very small (5–7 g) animalivorous phyllostomid, to explore whether broad resource use is associated with specific morphological, behavioral and performance traits within the phyllostomid radiation. We documented processing of natural prey and measured bite force in free-ranging M. microtis and other sympatric phyllostomids. We found that M. microtis had a remarkably broad diet for prey size and hardness. For the first time, we also report the consumption of vertebrates (lizards), which makes M. microtis the smallest carnivorous bat reported to date. Compared to other phyllostomids, M. microtis had the highest bite force for its size and cranial shape and high performance plasticity. Bite force and cranial shape appear to have evolved rapidly in the M. microtis lineage. High performance capacity and high efficiency in finding motionless prey might be key traits that allow M. microtis, and perhaps other species, to successfully co-exist with other gleaning bats.

Go big or go fish: morphological specializations in carnivorous bats

“…[30,[54][55][56][57]). These higher bite forces would facilitate prey processing, as prey hardness scales positively with size [58] and carnivorous bats are osteophagous [23,24,26]. Carnivorous bats span almost a sevenfold range in body mass (26-171 g; [20,22]).…”

“…Owing to these behavioural specializations, felids are restricted to prey that can fit between the canine teeth [68,69], and larger felids have evolved a longer rostrum and larger jaw adductors to take larger prey [60]. Some carnivorous bats are known to rely on similar behaviours to kill their prey [23,24], thus skull shape allometry would represent a mechanism to further increase their range of prey sizes. The fact that carnivorous bats also have evolved cranial features associated with high bite force provides additional support for the importance of wide gapes in the feeding ecology of these bats.…”

“…17 g) and, although not entirely distinct from insectivorous species, have a relatively elongate cranium, thin dentary, low condyles, large brain volume and large pinnae. Recent studies, however, indicate that large body size is not a requirement for the consumption of vertebrate prey in bats; Micronycteris microtis (7 g) has been documented to feed on small lizards in addition to insects [23]. Furthermore, some relatively large bats are insectivorous (e.g.…”

A New Family of Large Omnivorous Bats (Mammalia, Chiroptera) from the Late Eocene of the Fayum Depression, Egypt, with Comments on Use of the Name “Eochiroptera”

“…For bats, researchers have long distinguished "animal-eating" or "animalivorous" taxa from those that feed partly or entirely on plant products (Freeman, 1984(Freeman, , 1998(Freeman, , 2000Norberg and Fenton, 1988;Rex et al, 2010, Santana et al, 2011b. In this context, animalivory is an umbrella term that covers both insectivorous and carnivorous species, and those that fall somewhere in between (Freeman, 1984(Freeman, , 1998(Freeman, , 2000Norberg and Fenton, 1988;Santana et al, 2011aSantana et al, , 2011b.…”

“…As body size increases, some species with dilambdodont molar teeth often include small vertebrates in their diet. For example, large phyllostomines (e.g., Vampyrum spectrum, Chrotopterus auritus, Trachops cirrhosus), noctilionids (e.g., Noctilio leporinus), nycterids (e.g., Nycteris grandis), megadermatids (e.g., Macroderma gigas, Megaderma lyra, Cardioderma cor), and vespertilionids (e.g., Antrozous palidus, Nyctalus lasiopterus) variously consume small vertebrates including birds, lizards, frogs, fish, mice, and sometimes even other bats (Norberg and Fenton, 1988;Freeman, 1984Freeman, , 1998Dondini and Vergari, 2000;Santana et al, 2011aSantana et al, , 2011b. Body size alone does not predict carnivorous habits, however, since many midsized and some large animalivorous bats apparently do not feed on vertebrates but instead prey only on insects (e.g., Saccolaimus peli, Hipposideros commersoni, Cheiromeles spp.…”